Concrete screeds are used by personnel in the building industry to place and level uncured concrete to form a slab or floor. In its most simplistic form, a straightedge such as wooden 2″×4″ is pulled back and forth across the uncured concrete by one or more persons to level the concrete to a predetermined grade which has been previously determined and set using such methods as stakes, wet pads or metal tubing on supports. This manual screeding method requires skilled, physically capable personnel to achieve a quality floor or slab.
More recently different types of sophisticated screeds have been developed to obtain a more consistently level concrete surface using lasers to meet stricter standards of today's building industry. Large, self propelled, laser screeds such as developed by Somero et al., U.S. Pat. No. 4,655,633, are useful for placing huge easily accessible floors, but are not easily portable or useful on smaller floors. Similarly, truss screeds such as Morrison's U.S. Pat. No. 4,806,047, are more adaptable to use on very large jobs.
At the other end of the modern screed continuum are the hand held vibratory screeds, such as U.S. Pat. No. 5,676,489, and U.S. Pat. No. 5,540,519 which work well on smaller jobs and are readily portable, but rely on operator skill to achieve consistency of the finished product, even when grade is laser established. By simply tilting the screed apparatus during placement of the concrete, the result may be deflections and variations in the levelness of the concrete both horizontally and vertically to the operator.
In light of the prior art, a need still exists for a relatively inexpensive, lightweight, easily portable screed, which does not rely on operator experience and skill to achieve an on grade level floor.